stack and queue

#include <iostream>
#include <cstdio>
using namespace std;

struct list{
	int data;
	struct list *next;

	};
typedef struct list node;
	node *head;


void insert(int x){



	node *temp,*temp2;

	if(head == NULL){
		head = new node();
		head->data = x;
		head->next = NULL;
		temp = head;
		}
	else{

		temp2 = new node();
		temp2->data=x;
		temp2->next = NULL;
		temp->next = temp2;
		temp = temp2;

		}


	}

int len(node *head){
	int count=0;
	while(head !=NULL){

		count++;
		head = head->next;
		}

	return count;
	}

void stackQ(char x ){
	node *temp = head, *temp2;

	if(head->next == NULL)
			delete head;

	else if(x== 'D'){
		head = head->next;
		delete temp;

		}
	else{


		while(temp->next->next!=NULL){
			temp=temp->next;
		}
		temp2 = temp->next;
		temp->next = NULL;

		delete temp2;

		}


	}

void display(){
	node *temp = head;
	while(temp !=NULL){
		printf("%d ", temp->data);
		temp = temp->next;

		}
	cout<<endl;
	}

bool empty(){

	if( head == NULL)
		return true;

	return false;

}

int main(int argc, char **argv)
{

	head = NULL;

	insert(10);
	insert(20);

	insert(30);
	insert(40);


	stackQ('x');
	display();

	stackQ('D');
	display();


	return 0;
}